1. Field of the Invention
The present invention relates to an ophthalmological image-taking apparatus for use in an ophthalmic clinic or the like and to a method for changing a gain in the ophthalmological image-taking apparatus.
2. Description of the Related Art
For example, an ophthalmological image-taking apparatus disclosed in Japanese Patent No. 2,801,318 performs automatic exposure compensation. To provide an image with an automatically-adjusted light exposure, the image-taking apparatus determines a fundus refractive index from the amount of light illuminating an eye fundus and the amount of light reflected from the eye fundus, and controls the amount of light to be emitted from a fundus image-taking light source on the basis of the refractive index thereof.
In the example of the related art, however, optical members for extracting light flux need to be provided in the optical paths of an illumination optical system and an image-taking optical system.
As a result, a loss in the amount of image-taking light occurs, or mechanisms for inserting and retracting the optical members are required, thus resulting in a complicated structure.
In addition, the image-taking apparatus has problems in that a considerable amount of time is required from when the switch is pressed until an image is actually recorded and the accuracy of the image taking is reduced.
Accordingly, to overcome the foregoing problems, an object of the present invention is to provide an ophthalmological image-taking apparatus that controls the amount of emission light and that performs high-accuracy image-taking and recording with a simple structure.
Another object of the present invention is to provide a method for changing a gain in the ophthalmological image-taking and recording apparatus.
In order to achieve the foregoing objects, according to the present invention, the amount of light emitted from an image-taking light source for taking and recording an image is controlled in accordance with the amount of light emitted from an observation light source used for observing an eye fundus and with the intensity of a video signal.
In addition, in order to achieve the foregoing objects, according to the present invention, the amount of light emitted from the image-taking light source for taking and recording an image is controlled in accordance with the amount of light emitted from the observation light source for observing the eye fundus and with a gain for amplifying the video signal to a signal having a predetermined intensity.
Additionally, in order to achieve the foregoing objects according to the present invention, a gain for taking and recording an image of an eye to be examined is stored in storing means and the gain stored in the storing means is controlled in accordance with a video signal output, at the time of image-taking, from an image-capturing means.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.